Segment Reporting - Active Partner Companies by Segment (Detail)	Mar. 31, 2017
AdvantEdge Healthcare Solutions, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	40.10%
Apprenda
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	29.40%
BrickWork
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	20.30%
Cask Data
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	31.30%
CloudMine
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	47.30%
Clutch Holdings, LLC
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	42.80%
Full Measure
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	42.30%
Hoopla Software, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	25.50%
Lumesis, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	44.10%
MediaMath, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	20.50%
Moxe Health
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	32.40%
Pneuron
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	35.40%
Prognos
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	35.20%
QuanticMind, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	23.20%
Sonobi
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	21.60%
Spongecell
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	23.00%
T-REX Group, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	23.60%
Transactis
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	24.00%
WebLinc
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	38.00%
Healthcare | Aktana, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	31.20%
Healthcare | Good Start Genetics, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	29.60%
Healthcare | InfoBionic
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	39.70%
Healthcare | meQuilibrium
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	31.50%
Healthcare | Novasom, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	31.70%
Healthcare | Propeller
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	24.00%
Healthcare | Syapse, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	26.20%
Healthcare | Trice
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	27.60%
Healthcare | Zipnosis
Schedule of Equity Method Investments [Line Items]
Ownership interest under equity method, percentage	25.40%